Field of the Invention
This invention relates to an automatic buttonhole stitching device of a computerized sewing machine for repeating buttonhole stitches of the same size.
When buttonhole stitches of the same size are repeated by means of a computerized sewing machine and if a trial stitching is made with a required size to an object button, data concerning the size of the buttonhole stitch in said trial stitching, are temporarily stored in a memory, and buttonhole stitches following the first buttonhole stitch are repeatedly formed with the same size in accordance with the stored data.
However, it is difficult to obtain buttonholes of the required size by one trial stitching, and lengths of right and left line tacks are often made unbalanced. Therefore, the trial stitchings are ordinarily made several times and a button is passed therethrough, to obtain a size of a buttonhole as desired while making confirmations.
For making the trial stitches, a machine operator confirms whether previous stitches are proper or not, and visually refers to the confirmed trial stitches in order to visually decide on a new size or repeat the stitches. Thus, the proper buttonhole size is selected.